The present invention relates to a method for the manufacture of a component assembly comprising a sheet metal part and a functional element attached to it by a riveting process or by a riveting and piercing process or by a press-in process, wherein the sheet metal part is provided with an imprint. Furthermore the invention relates to a sheet metal part as well as to a functional element which are suitable for use in the method.
A method of the initially named kind is known from the European Patent 0 539 793 and is described there with a functional element in the form of a rivet nut. There a sheet metal part is provided with a stamped formation or imprint in the form of a ring-like collar around a pre-pierced hole and a cylindrical rivet section of the functional element is introduced into the stamped hole from the side of the ring collar which projects beyond the plane of the sheet metal part so that a ring-like contact surface of the functional element which forms the transition between the body of the nut element and the cylindrical art comes into contact against the end face of the ring-like collar. Triangular, nose-like ribs providing security against rotation are provided in the transition region between the ring-like contact surface and the cylindrical rivet section. Following this the nut element is pressed against the sheet metal part so that the cylindrical rivet section is formed by means of a die button arranged below the sheet metal part into a rivet bead and the ring-like collar which has a conical shape is pressed at least partly flat. In this way the diameter of the pierced hole is reduced and the outer diameter of the rivet section simultaneously enlarged so that a considerable “stranglehold” takes place between the sheet metal part and the nut element around the rivet section. Furthermore, the noses providing security against rotation are pressed into the sheet metal material of the sheet metal part and serve for an excellent security against rotation.
A related method is also used for the attachment of so-called RND elements (European Patent 11116891) to sheet metal parts.
The fastener elements in accordance with the European Patent 0 539 793 and EP 11116891 are so-called rivet elements which are inserted into pre-pierced holes in the sheet metal part and are secured to the sheet metal part by a rivet process. It is, however, not essential to pre-pierce the sheet metal part but rather fastener elements also exist which are riveted to a sheet metal part without the rivet section of the element penetrating the sheet metal part. This is for example the case in the rivet element of EP-A-0 993 902. Furthermore, functional elements exist which are attached by a so-called riveting and piercing process to a sheet metal part. For example, the SBF bolt elements of the company Profil-Verbindungstechnik GmbH & Co. KG, which are described in the German patent specification 34 47 006 and the corresponding nut elements, which are attached by a like method to a sheet metal part, fall in this category. However, with these elements the sheet metal part is not provided with a pre-formed imprint prior to the attachment but rather the imprinting of the sheet metal part takes place during the attachment of the functional element in a first stage of the attachment method.
Furthermore, so-called press-in elements are known in the prior art which are pressed into the sheet metal part and indeed in such a way that the sheet metal part flows to a certain extent around the element and leads to a form-locked engagement of the element with the sheet metal part without an actual riveting process taking place. An example for a press-in element and a press-in process of this kind is the so-called EBF element of the company Profil-Verbindungstechnik GmbH & Co. KG which, together with the method for its attachment, is described in the European Patent 0 678 679 B and in the later European patent specification EP-B-0958100. The last-named European patent specification also describes a possibility of introducing an EBF element in self-piercing manner into a sheet metal part. The RND elements described above as rivet elements can also be introduced in self-piercing manner in the sheet metal parts, even if this is not frequently practiced.
The designation functional element is however not restricted to fastener elements but rather counts in the specialist field as a designation for a large number of other elements which satisfy specific functions and which can be secured by riveting processes, by piercing riveting processes or by press-in processes to sheet metal parts. By way of example the above-named EP-B-120234 describes amongst other things, a functional element which is secured with a piercing and riveting process to a sheet metal part, with one realization of the corresponding element taking place in the form of a so-called ball pin. The corresponding element is described in the European patent application EP-A-01989624.0, with the spherical head of this element serving to accommodate a ball socket in order, for example, to be used in a gas support strut for a motor vehicle hood or rear door. Furthermore, functional elements are known which serve as spigots for the turning of rotatable parts or are for example provided with a clip mount which serves for the clipped attachment of carpets, brake lines or cable looms in motor vehicles. Furthermore, functional elements having a fir-tree-like structure are known which can be used for lower level attachment purposes in conjunction with hollow parts which are pressed onto the fir-tree structure.